1. Field of the Invention
The present invention is directed to the field of alignment devices.
2. Description of the Related Art
People undertaking construction and repair projects frequently require the use of reference guides. People employ reference guides on projects ranging from professional construction of large city buildings to amateur home improvement. For example, a person installing a border on the walls of a room requires a level reference line on each wall identifying a placement position for the border.
Traditional alignment tools for assisting in the manual placement of reference guides include straight edges, rulers, protractors, squares, levels, and plumb bobs. More recently, tool manufacturers have introduced laser alignment devices that provide references, such as points, lines, and planes. These laser alignment tools include, simple pointers, pointers with bubble vials, self-leveling pointers, multiple beam pointers, and devices producing a sheet of light.
In many instances a project requires the use of multiple references. For example, a project may require the use of both reference lines and planes in horizontal and vertical orientation. In many instances this requires the use of multiple alignment toolsxe2x80x94forcing a person to have all of these tools available for the project. The purchase, maintenance, storage, and transportation of several alignment tools are undesirable inconveniences that consume time and money. In some circumstances it is simply impractical to have multiple alignment tools readily available on a job site.
It is desirable for a single alignment tool to provide multiple types of references in both horizontal and vertical orientations. This reduces the number of tools required for a jobxe2x80x94allowing users the convenience of purchasing, maintaining, storing, and transporting a reduced number of tools. The user""s convenience in using a multiple reference tool, however, must not be outweighed by the expense of the tool. The multiple reference alignment tool also needs to meet the user""s accuracy expectations.
In electro-mechanical control systems, such as an automated reference tool, backlash can be a leading source of inaccuracy. In a control system, the movement of a first object directs the motion of a second object. Backlash is the phenomenon of mechanical hysteresis that occurs when the direction of motion of the first object is altered. Mechanisms controlling the motion of the second object by directing the motion of the first object need to account for backlash. Otherwise, the control system""s accuracy will be compromised. A multiple reference alignment tool needs to either reduce or compensate for backlash in all of the orientations the tool will be used.
Traditional systems frequently employ expensive high precision components to overcome the problem of backlash and minimize other sources of inaccuracy. However, this can result in increasing the expense of a reference tool beyond the acceptable threshold of many users. It is desirable to reduce backlash effects and other inaccuracies without necessitating the use of expensive components.
The present invention, roughly described, pertains to an alignment device capable of providing multiple references in different orientationsxe2x80x94reducing the number of alignment devices a user needs for a job site. One implementation of the alignment device provides a horizontal set of laser references and a vertical set of laser references. For each set of references, users have the ability to select a plane, line, or pointing reference. In one version of the alignment device, users can also rotate the position of the vertical and horizontal reference points and lines. In a further embodiment, users can adjust the positions of the laser planes on incident surfaces.
One embodiment of the alignment device includes an optics mounting assembly mounted in a pivot socket on a frame. Three spring systems and one or more alignment assemblies secure the optics mounting assembly in the pivot socket and provide for movement of the optics mounting assembly with reduced backlash. The optics mounting assembly includes a light source supplying a light beam. In one embodiment, the light source is a laser emitting diode supplying a laser beam. The source beam is incident on a reflector that produces an output reference beam. At rest, the reflector produces a reference point. A motor mounted on the optics mounting assembly spins the reflector to generate a reference plane. The motor dithers the reflector to generate a reference line. In a further embodiment, a user can manually position the output reference beam.
One implementation of the pivot socket has a surface in the form of a sphere""s interior surface. The optics mounting assembly extends through the pivot socket and includes a set of support members that rest on the pivot socket""s spherical surface. The support members hold the reflector in a position that results in the output reference beam originating at the center of a sphere that includes the pivot socket""s spherical surface. This minimizes translation of the output reference beam""s origin when the optics mounting assembly pivots in the socket.
A first spring system includes a set of springs exerting force on the optics mounting assembly. The spring forces hold the optics mounting assembly support arms against the spherical surface of the pivot socketxe2x80x94directing the optics mounting assembly through the pivot socket. In one implementation, a resultant force from the first spring system is directed along an axis that is perpendicular to a cross-section of an opening in the pivot socket that receives the optics mounting assembly. The optics mounting assembly includes a set of extension arms that communicate with the alignment assemblies. A second spring system biases the extension arms against the alignment assemblies. The alignment assemblies apply forces on the extension arms that oppose the force effects of gravity and extraneous impacts on the optics mounting assembly. The forces from the first spring system and alignment assemblies hold the optics mounting assembly in a desired position within the pivot socket. In one embodiment, the optics mounting assembly is always positioned so that movement of the optics mounting assembly is about a pivot point at the center of a sphere that includes the spherical surface of the socket.
Alignment assembly movements direct the movement of the optics mounting assemblyxe2x80x94altering the position of the output reference beam. In one embodiment, the alignment device includes a level sensor that supplies signals indicating whether the optics mounting assembly is normal to true level. A control subsystem in the alignment device employs these signals to drive the alignment assemblies. The alignment assemblies provide forces to the optical mounting assembly extension armsxe2x80x94positioning the optics mounting assembly normal to true level. This results in an output reference beam parallel to true level. In one embodiment, the alignment assemblies pivot the optics mounting assembly about a pivot point at the center of a sphere that includes the spherical surface of the socket.
The first and second spring systems assist in removing backlash from the alignment device""s controlled movement of the optics mounting assembly. The second spring system holds the extension arms flush against pads on the alignment assemblies. The optics mounting assembly support arms are held flush against the spherical surface of the pivot socket by the combined forces of gravity and the first spring system.
In one implementation, each alignment assembly pad is mounted on a lead screw with a gear driven by a motor controlled pinion. The pinion""s teeth are tightly coupled to the gear""s teeth to further reduce backlash. The pinion and gear are drawn together by a spring force from a third spring assembly that allows the gear and pinion teeth to separate, as needed, to minimize backlash and compensate for run-out.
The alignment device also produces an accurate reference beam when the device is rotated by ninety degreesxe2x80x94converting a horizontal laser plane generated by the reference beam into a vertical laser plane. The spring systems and alignment assemblies provide the same forces in the rotated orientation to secure the position of the optics mounting assembly and remove backlash effects. In such an implementation, the alignment assemblies can be employed to control the positioning of the output reference beam on an incident surface. For example, the alignment assemblies may horizontally translate a vertical laser plane output on the incident surface.
Further implementations of the alignment device include additional features for enhancing accuracy. For example, the reflector can be a penta-prism mounted with a predefined pitch for reducing the effects of satellite output beams. The penta-prism may also include a predetermined pitch deviation. The penta-prism is then mounted within a known roll range to achieve a more accurately positioned reference beam.
Alignment devices in alternate embodiments of the present invention may provide less than all of the references described above. One version of an alignment device according to the present invention only provides a single type of reference in a single orientation.
Aspects of the present invention can be accomplished using hardware, software, or a combination of both hardware and software. The software used for the present invention is stored on one or more processor readable storage media including hard disk drives, CD-ROMs, DVDs, optical disks, floppy disks, tape drives, RAM, ROM or other suitable storage devices. In alternative embodiments, some or all of the software can be replaced by dedicated hardware including custom integrated circuits, gate arrays, FPGAs, PLDs, and special purpose computers.
These and other objects and advantages of the present invention will appear more clearly from the following description in which the preferred embodiment of the invention has been set forth in conjunction with the drawings.